The influence of cryotherapy (Cryotron®) on pain and inflammation following arthroscopy of the shoulder

Prof Dr Ro main Meeu sen Dr Fra nk Hand elberg , Lau rence Fr amhou t, Sté phan ie Daems Vr ije Univer siteit Brussel Belgiu m

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Abstract Objective: To examine the influence of cryotherapy on subacromial temperature, pain and inflammation in the postoperative shoulder Participants: Twenty patients undergoing diagnostic shoulder arthroscopy Intervention: Cold was administered via a Cryotron® , a second group received a ‘placebo’ treatment, while a third group served as control. Visual analogue scores (VAS) were used to obtain pain scores and a patientcontrolled analgesia system (PCA) was applied to standardize post operative medication. C-reactive proteins (CRP) were measured to get an idea of the inflammatory reaction. Results: Skin temperatures differed significantly after post operative cryotherapy. Cryotron® treatment resulted in a very steep temperature drop during the first minute of application. Subacromial temperature was significantly lower for the Cryotron® group during the night (when no cold was applied). According to the results of this study, cryotherapy has a positive effect on reducing post operative pain. Both VAS values and medication use were lower in the experimental groups. CRP measurements did not reduce significantly due to cryotherapy, but it seems that cryotherapy used suppresses the inflammatory reaction, as shown by one case with acute gout. Conclusion: These results indicate that postoperative pain is influenced significantly when cryotherapy is applied. Keywords: Cryotherapy, Inflammation, C-reactive proteins, Cold therapy, Pain

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Introduction The use of cryotherapy dates back to the time of the Acient Romans and Greeks. The only cooling modalities in those times were ice and snow. Today, advances in the delivery of cryotherapy have resulted in greater postoperative use (Swenson et al., 1996; Levy et al., 1997). The use of cold for the treatment of musculoskeletal injuries, whether caused by athletic injuries or by surgery, is generally accepted but largely based on empirical evidence. Unfortunately, this unanimity in the use of cold treatment has somewhat masked the physiological fundamentals and the mechanism by which it is effective in controlling pain and enhancing comfort is not fully understood. (Meeusen et al., 1998; Meeusen and De Meirleir, 1991; Swenson et al., 1996; Meeusen and Lievens, 1986; Scheffler et al., 1992; Levy et al., 1997; Speer et al., 1996; Fedorczyk, 1997). Besides the analgesic effect, cryotherapy is also believed to decrease inflammatory reaction, edema and haematoma formation. Physiological reactions such as vasoconstriction and decrease in blood flow, nerve conduction velocity and muscle spasm have also been attributed to the therapy (Meeusen et al., 1998; Meeusen and De Meirleir, 1991; Swenson et al., 1996; Ivey et al., 1994; Levy et al., 1997). Cold application obviously influences tissue temperature, and this temperature reduction depends on the application method, it’s temperature, and the application time (Meeusen and Lievens, 1986; Speer et al., 1996; Meeusen and De Meirleir, 1991; Swenson et al., 1996). Several studies have examined the effects of cryotherapy on rehabilitation following knee surgery, but only few investigated the efficacy of cold application in the postoperative shoulder. Until now no study examined the effects of different cryotherapy applications on both skin and intra-articular temperature in combination with pain measures and inflammatory parameters. Therefore the purpose of this study, is to examine the effect of cryotherapy on skin temperature, subacromial temperature, pain and inflammation in the postoperative shoulder.

Materials and Methods

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Subjects

In this randomized, prospective study twenty patients (6 men and 14 women) underwent diagnostic shoulder arthroscopy, if necessary preceded by mobilisation under narcosis. The mean age of the participants was 49,6  7,2years. The procedures included shaving of the acromion and acromioclavicular resection. Patients clinically diagnosed with instability problems or those needing an open cuff repair were excluded. All operations were performed under general anaesthesia and by the same surgeon (F.H.) to ensure standardized procedures. At the end of surgery, a temperature probe type 400 (Smiths Industries, Irvine, CA, U.S.A.) with an accuracy of 0,2°C was placed under direct arthroscopic vision into the subacromial space. Procedure The study protocol and design and the Informed Consent form were approved by the ethical commission of the Vrije Universiteit Brussel. In a randomized fashion, cold was administered by Cryotron® (Cryonic Médical France). This methods uses a brief application (45 sec) of high pressure (50 Bar), cold air (-78°C) with a specific “pistol” to the area of interest (45 cm2). The pistol was held at a distance of 10 cm from the skin. Two areas of the shoulder were treated i.e. the “acromion” surface and the “deltoid” region. This treatment cycle was repeated every 3 hours.

We used a placebo group. In the placebo group a “spraying of the shoulder region” with the same pistol was used. No cold air, nor pressure was used. CRYONIC MEDICAL Copyright ©

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For reasons of comparison (CRP measures) a control group with no treatment was included. Cryotherapy was stopped during the night to assure the patient a good night’s rest.

Measurements The patients were informed of the study design and each of them signed an informed consent form. A clinical and therapeutical examination followed. Since cold penetration depends on the depth of the target tissue (Meeusen and De Meirleir, 1991), we found it necessary to measure the tissue surrounding the shoulder. Therefore an echography was taken to determine the thickness of the subcutane fat layer and the M. deltoideus. Skin temperature was measured using an adhesive temperature sensor type STS400 (Smiths Industries, Irvine, CA, U.S.A.) on the lateral part of the shoulder. Temperature was measured every hour, T 0 representing the start of the measurements. For the Cryotron® patients temperature was registered immediately after application during the first 60 sec with time intervals of 5 seconds. This procedure was followed because the temperature drop was the steepest in the first 60 secs after application. The next measurement was 30 min later and 1 and 2 hours after the cold application. Intra-articular temperatures were recorded immediately after application at 30 and 60 seconds, and at the same time as skin temperatures. During the night temperature was registered every 2 hours until the next morning. Painscores were obtained by a visual analog scale (VAS). The first VAS was taken the day before the operation. Postoperative we started at the recovery room. Registration took place together with temperature measurements. To standardize analgesia, a patient-controlled analgesia system with Dipidolor was used. This way the patient provides his own intravenous medication supply by pushing a button. A lock-out interval of 10 minutes was imposed to avoid overdosis. Per dosis the patient received 2mg or 1ml Dipidolor. The maximum amount in 4 hrs was 30mg. The total amount of dipidolor (mg), the number of PCA requests (= demand) and the number of successful administrations (= delivery) were stored by

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the PCA device. The morning after surgery the system was removed. Our patients were not allowed to receive any other medication for the duration of the study. C-reactive proteins (CRP) in blood plasma were measured as an indication of inflammation. In our study 3 blood samples were collected. The first one was taken 1 day pre-operative, the second one 6 hours after starting the measurements and the last one the first day postoperative. The detection limit was